Long-Term Trend Analysis of Precipitation and Air Temperature for Kentucky, United States

Variation in quantities such as precipitation and temperature is often assessed by detecting and characterizing trends in available meteorological data. The objective of this study was to determine the long-term trends in annual precipitation and mean annual air temperature for the state of Kentucky. Non-parametric statistical tests were applied to homogenized and (as needed) pre-whitened annual series of precipitation and mean air temperature during 1950–2010. Significant trends in annual precipitation were detected (both positive, averaging 4.1 mm/year) for only two of the 60 precipitation-homogenous weather stations (Calloway and Carlisle counties in rural western Kentucky). Only three of the 42 temperature-homogenous stations demonstrated trends (all positive, averaging 0.01 °C/year) in mean annual temperature: Calloway County, Allen County in southern-central Kentucky, and urbanized Jefferson County in northern-central Kentucky. In view of the locations of the stations demonstrating positive trends, similar work in adjacent states will be required to better understand the processes responsible for those trends and to properly place them in their larger context, if any

Effects of Biochar Treatment of Municipal Biosolids and Horse Manure on Quality of Runoff from Fescue Plots

Land-applied horse manure and municipal biosolids can increase nutrient and bacteria concentrations in runoff. Biochar has been demonstrated to have beneficial impacts on nutrient retention and runoff quality when used to treat other land-applied organic soil amendments (e.g., poultry manure). The objective of this study was to evaluate the effects of biochar addition to horse manure and municipal biosolids on runoff concentrations of nutrients and fecal coliforms. Biochar was added at 5% to 8% (wet basis) to horse manure and biosolids that were applied to 2.4 m x 6.1 m fescue plots followed by application of simulated rainfall (102 mm h-1). Analysis of runoff samples indicated that soil hydraulic characteristics, as reflected in the runoff curve number (CN), were a significant covariate for some analytical parameters. Analysis of covariance indicated that biochar addition decreased runoff concentrations of total Kjeldahl nitrogen (TKN) and ammonia nitrogen (NH3-N) when added to municipal biosolids, with all effects more prominent at higher CN values. When added to horse manure, biochar decreased runoff concentrations of NH3-N, total suspended solids, and fecal coliforms. Although runoff concentrations of total P and TKN increased with CN, there was no significant biochar effect on these parameters when added to horse manure. The findings indicate potential for biochar addition to improve runoff quality when added to these organic amendments, but the effects may be dependent on the receiving soil‘s runoff production characteristics

The Development of Relationships Between Constituent Concentrations and Generic Hydrological Variables

The collection and analysis of samples from storm events constitutes a large portion of the effort associated with water quality research. Estimating concentrations or loads from these events is often difficult. The equipment necessary to analyze the samples and the required laboratory resources are typically significant expenses incurred by the researcher. One potential method to reduce these costs is through the development of generic relationships between concentrations and easily measured variables such as dimensionless flow rate or time. The benefits recognized from such an effort include a reduction in the number of required samples, resulting in a reduction in cost. Using data collected from an Arkansas stream near Fayetteville, relationships between the generic variables (time and flow) and several constituents (nitrate–N, orthophosphate, total phosphorus, ammonia–N, total Kjeldahl nitrogen, chemical oxygen demand, total suspended solids, fecal coliforms, and fecal streptococci) were examined. Results of the analyses indicated that a form of the gamma function could be used to estimate the flow–weighted mean concentrations and loads of the constituents at a significant cost savings to the user, assuming that single–peak hydrograph data were readily available. By using a single sample collected at the peak of the storm along with information pertaining to the time of sample collection, time of the peak of the storm hydrograph, and the constituent concentration of the sample, the flow–weighted mean concentration or load could be determined. Results of the analysis indicate that the method performed reasonably well. Since the analysis of only one sample is required to determine the flow–weighted mean concentration or load, instead of several samples, this method is quite appealing to users on a limited budget

A Direct, Approximate Solution to the Modified Green-Ampt Infiltration Equation

Accurately predicting the rainfall-runoff process is of vital importance for water quality models as well as for correct design of various types of hydraulic structures. This article presents a method of describing the cumulative infiltration process as an explicit function of time using an approximation to the modified Green-Ampt equation given by Mein and Larson (1971). The resulting equation is helpful in predicting cumulative infiltration and therefore infiltration capacity for computer simulation models. The proposed method takes about 50% less time than the usual iterative technique for the same degree of accuracy. The maximum error due to approximation was 1% and generally the error was much less, making this solution acceptable for most practical problems

Runoff Quality Responses to Cattle-Gazing Strategy and Grassed Buffer Zone Length

Grazed pastures represent a source of potential nonpoint pollution. In comparison to other nonpoint sources (e.g., row-cropped lands), relatively little information exists regarding possible magnitudes of pollution from grazed pasture; how that pollution is affected by weather, soil, management and other variables; and how the pollution can be minimized. The objective of this study was to assess how the quality of runoff from simulated grazed pasture is influenced by grazing duration (4-12 weeks), grazing strategy (no grazing, conventional grazing and rotational grazing), and by the use of grassed buffer strips (ranging in length from O to 18.3 m) installed down-slope of simulated pasture. The study was conducted at the University of Kentucky Maine Chance Agricultural Experiment Station north of Lexington. Plots (2.4 m wide by 6.1 to 30.5 m long) were constructed and established in Kentucky 31 tall fescue (Festuca arundinacea Schreb.) to represent pasture. Grazing was simulated by application of beef cattle manure to the plots. Runoff was generated by applying simulated rainfall. Runoff samples were collected and analyzed according to standard methods for nitrogen (N), phosphorus (P), total suspended solids (TSS), and fecal coliform (FC). Runoff concentrations and transport of N and P from the plots used to simulate conventional and rotational grazing were low and, in many cases, not different from those measured for ungrazed plots. Runoff FC concentrations were greater for the simulated grazed plots than for the control plots, but there was no difference in concentrations between the simulated conventional and rotational grazing treatments. The buffer strips were very effective in removing TKN, P04-P, TSS and FC in incoming runoff from manured plots. Concentrations of all these parameters were indistinguishable from background levels after crossing a buffer length of 6.1 m. This finding is attributed largely to very high infiltration in the plots used to assess the buffer strips

Response of Runoff Diazinon Concentration to Formulation and Post-Application Irrigation

Pesticides used in urban environments can be transported in runoff to downstream waters and cause adverse environmental consequences. This experiment assessed the effects of post-application irrigation depth (0, 6.4, and 12.7 mm) and formulation (liquid and granular) on concentration and transport of diazinon (a pesticide commonly used for lawn insect control) in runoff from “tall” fescue (Festuca arundinacea Schreb.) plots. The post-application irrigation was applied using rainfall simulators immediately following diazinon application. The rainfall simulators were again used approximately 2 h after diazinon application to apply the equivalent of a heavy rainfall (64 mm/h for approximately 1.5 h) to generate runoff. Runoff was sampled and analyzed for diazinon using the enzyme-linked immuno-sorbent assay method. Post-application irrigation depth had no effect on diazinon concentration but increased diazinon mass transported off the plot by increasing plot runoff. Flow-weighted mean runoff diazinon concentration for the liquid formulation of diazinon was roughly double that of the granular formulation (0.59 vs 0.29 mg/L), attributed to the higher solubility of the liquid formulation relative to the granular formulation. The results indicate that post-application irrigation can increase runoff losses of diazinon for heavy rainfall occurring soon after application, but that these losses can be reduced by use of the granular formulation

Runoff from Fescue Plots Treated with TRIMEC

Runoff of herbicides can promote adverse impacts in receiving waters. The objective of this study was to assess the effects of rainfall delay, herbicide application rate, rainfall intensity, and pre-application rainfall on runoff of TRIMEC (a combination of 2,4-D, dicamba, and mecoprop), a herbicide that is commonly used in central Kentucky. The levels of rainfall delay were 0, 2, and 4 d following application; and the levels of herbicide application rate were 0, 0.5, 1 and 2 times the recommended rate. Simulated rainfall was applied at intensities of 64, 102, and 140 mm h-1; and the depths of water applied prior to TRIMEC application were 0, 13, and 25 mm. Flow-weighted composite runoff samples were analyzed by gas chromatography. Maximum concentrations in runoff for treatment combinations studied were: 2,4-D, 45.5 µg L-1; dicamba, 1.59 µg L-1; and mecoprop, 212 µg L-1. The rainfall delay affected both 2,4-D and dicamba concentrations but not mecoprop concentration, suggesting that its foliar half-life might be longer than suggested. As anticipated, runoff concentrations of all TRIMEC constituents were significantly (p \u3c 0.05) affected by herbicide application rate. Rainfall intensity affected only the concentration of mecoprop, with concentrations at the highest intensity being significantly (p \u3c 0.05) greater than those at the two lower concentrations. Pre-application rainfall had no significant effects on runoff concentrations. Mass transport averaged 1.51, 0.38, and 14.8% of amounts applied for 2,4-D, dicamba, and mecoprop, respectively, reflecting differences in degradation rates, wash-off characteristics and other factors. Mass transport was in no case significantly affected by the treatments. The findings of this study suggest that when TRIMEC is applied at the recommended rate under comparable soil, vegetation and weather conditions, the potential for 2,4-D to exceed the maximum contaminant level of 70 µg L-1 in runoff is low

Vegetative Filter Strip Design for Grassed Areas Treated with Animal Manures

Vegetative filter strips (VFS) are a low-cost management option that have been demonstrated to be effective in reducing runoff transport of fertilizer constituents applied to grassed areas (pasture or meadow). Runoff quality studies involving fertilizers applied to grassed areas suggest that VFS can be designed by assuming that (1) only infiltration is responsible for pollutant removal, (2) the first post-application runoff event is most important from a water quality perspective (enabling a design event approach), and (3) no pollutant build-up that degrades VFS performance will occur. The purpose of this study was to develop a VFS design algorithm for grassed areas that uses available information on the water quality dynamics of these systems to simplify the design process to the greatest degree practical. The design algorithm consists of the SCS (1972) Curve Number method for runoff estimation and the Overcash et al. (1981) equation for predicting concentrations of pollutants exiting a VFS as a function of VFS and runoff parameters. The procedure can be used to determine the VFS length required to meet either an allowable pollutant runoff concentration or allowable pollutant mass transport. As an alternative, the process can be used to determine VFS length required to achieve given relative reductions in incoming pollutant runoff concentrations and mass transport. This algorithm can be used quickly and with minimal data to determine the VFS length requirement necessary to provide any desired degree of effectiveness given inputs such as incoming pollutant runoff concentration, background pollutant runoff concentration, soil hydrologic properties, and design storm parameters. Charts are presented that eliminate the need for computations in selected cases

Quality of Runoff from Plots Treated with Municipal Sludge and Horse Bedding

Land application of horse stall bedding and municipal sludge can increase runoff concentrations of nutrients, organic matter, and bacteria as well as steroidal hormones such as estrogen. Concentrations of materials in runoff from sites treated with animal manure can be reduced by aluminum sulfate, or alum [Al2(SO4)3•14H2O] treatment. The objectives of this study were to assess plots treated with horse stall bedding or municipal sludge for: (a) runoff quality [concentrations of nitrate nitrogen (NO3-N), ammonia nitrogen (NH3-N), orthophosphate-phosphorus (PO4-P), fecal coliform (FC), chemical oxygen demand (COD) and 17- β estradiol (17 β-E, a form of estrogen)]; (b) changes in runoff quality caused by alum treatment; and (c) time variations in concentrations of the analysis parameters. Horse bedding and municipal sludge were applied to twelve 2.4 × 6.1 m fescue plots (six each for the bedding and sludge). Three of the bedding-treated and three of the sludge-treated plots were also treated with alum. Simulated rainfall (64 mm/h) was applied to the 12 treated plots and to three control (no treatment) plots. The data were analyzed as originating from separate completely randomized, one-way designs with three replications of each treatment. The first design had treatment levels of bedding, bedding and sludge, and control, while the second design had treatment levels of sludge, sludge and alum, and control. The control data were common to both designs. The first 0.5 h runoff was sampled and analyzed for the parameters described above. Analysis parameter concentrations for the waste treated plots were generally lower than those previously reported for runoff after organic treatments. In some cases, concentrations were no different from the controls. Mass losses of all parameters were low and agronomically insignificant. Alum addition decreased runoff PO4-P concentrations and increased NO3-N concentrations but had no effect on concentrations of other parameters. A significant effect of alum addition on 17 β-E and COD concentrations was anticipated on the basis of previous studies; its absence might have been due to inadequate mixing or interval between addition and simulated rainfall. Relationships between concentration and collection time followed two patterns: (a) highest concentrations occurring during the first sample (two minutes following runoff initiation; NO3-N, COD, FC and 17 β-E) and (b) delay in peak concentration until four minutes following runoff initiation (NH3-N and PO4-P). The detection of different general relationships between concentration and time suggests that different mechanisms are dominant in transport of the parameters analyzed

The Effect of Turfgrass Maintenance on Surface-Water Quality in a Suburban Watershed, Inner Blue Grass, Kentucky

Nutrients and pesticides applied during routine maintenance or establishment of turfgrass could result in nonpoint-source pollution. Nutrient and pesticide concentrations in water exiting a turfgrass management area in the Sinking Creek watershed, a suburban watershed in the Inner Blue Grass Region of central Kentucky, were monitored. This watershed was selected because it contains multiple land uses: agricultural, residential, and recreational (golf course). A survey was conducted to determine the extent to which lawn-care products are used in the residential sector of the watershed. For the golf-course portion, the golf-course superintendent recorded chemical application daily. Runoff from the golf course was sampled in 1993 where the stream exits the golf-course property. Sinking Creek was sampled upstream and downstream of the Tashamingo subdivision from April through October 1996 and January through February 1997. Weekly grab samples and three storm sample sequences (spring, summer, and fall) were analyzed to determine pesticide and nutrient concentrations. The analysis results revealed that few instances of pesticide concentrations in Sinking Creek exceeded minimum detectable levels and none exceeded the U.S. Environmental Protection Agency drinking-water limits during the sampling period. The herbicide 2,4-D was detected in Sinking Creek at both sample locations. In addition to 2,4-D, the insecticide chlorpyrifos was detected at the golf-course exit. Increases in pesticides and nutrients in Sinking Creek coincided with spring application of turfgrass chemicals in the suburban portion of the watershed. Concentrations of nitrogen and phosphorus were low and similar to what would be expected for the land use